The study deals with the chemical mechanisms whereby arthropods interact with other organisms in their environment. Particular attention is being given to substances that serve for protection against predators or microorganisms, or for communication with mates or siblings. The substances are being studied from the chemical, iochemical, and ecological points of view, in hopes of clarifying both their basic and applied significance. BIBLIOGRAPHIC REFERENCES: Conner, W.E., T.H. Jones, T. Eisner and J. Meinwald. Benzoyl cyanide in the defensive secretion of polydesmoid millipeds. Experientia 33, 206 (1977). Jones, T.H., J. Meinwald, K. Hicks and T. Eisner. Characterization and synthesis of volatile compounds from the defensive secretions of some "daddy longlegs" (Arachnida: Opiliones: Leiobunum spp.) Proc. Nat. Acad. Sci. 74, 419-422 (1977)